Well, reading through this thread I'm not even totally sure what we're talking about except that it has something to do with sharpening knives. I will not work with dull tools, but I know there are different types of edges you need for different types of work. If you're going to cut meat you will do better if the edge is ragged on a microscopic level. If you strop your knife with a smooth bar of steel you'll have a bur that does the cutting. If you smash a chunk of obsidian or chert, you'll have a rough sharp crystalline edge that will cut. That same edge will not hold up to woodworking chores, one of the final things some people do with a woodworking blade is make one pass with the finest stone, right across the edge. Squares it off a little bit. That actually works better than a razor sharp edge but it isn't a butcher's tool. I'm not sure about what it takes to cut hair, I quit cutting mine in the early 90's when it started moving to the back of head anyway.

That thing about fast healing makes sense to me, one of the old surgeon's tricks from the Civil War days was to cut a slash through a bullet wound, a straight cut heals faster than a hole. Rough edges make sense in the same way, increases the surface area of the cut.

Velocity counts. I was whittling a piece of wood in the early 70's with a razor sharp knife, which slipped. Sent the tip of one finger flying across the room. Fortunately, just a little bit of it, it healed up ok. There was no argument about edge efficiency, it just went sailing away.

JimmyTH

jimmy
quote"
Velocity counts. I was whittling a piece of wood in the early 70's with a razor sharp knife, which slipped. Sent the tip of one finger flying across the room. Fortunately, just a little bit of it, it healed up ok. There was no argument about edge efficiency, it just went sailing away."
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lets see - razor sharp - it slipped - it cut a finger tip off.
thank you... Hellooooo
Jim

Velocity counts.

Yeah. With less velocity the tip of your finger might have simply plopped listlessly at your feet rather than flying across the room.

Ok, Jim. We need to agree on a definition of 'sharp'. When I talk about a sharp knife, I'm talking about a good edge made by sharpening with a stone by hand, in fairly short order. I'm not talking about a machined edge that can split atoms. Truely dull knives are dangerous because you need to use excessive force to cut, and may in fact end up breaking or crushing rather than slicing. Do I want my knives as sharp as some specialized tools? No. Do I want them sharp enough to cut, unlike many peoples kitchen knives? You bet! One of the gifts I give my friends is to sharpen their kitchen knives whenever I use their kitchens. Knives should slice otherwise you just have a splitting tool with a short handle.

tcook
I think we agree. I've just been taking my time showing you that you agree with the concept that "sharp enough for the job" is probably the maximum sharpness that any edge should have, for safety reasons, if not for the difficulty of maintaining a "Dryer" edge for instance.

You know exactly the dull that happens to kitchens knifes that get washed a lot. I'll take a butcher knife and run each side over a long steel about twice. After that it sails through zuccini but its still not really sharp. The edge isn't honed smooth, its kinda ragged from a steel. If it cuts you, you may feel the pain and remove the pressure before it hits the bone.

This is what I call a "dull knife" - [relative to SHARP], from Jim's dull knife standard. Sharp enough to cut zuccini and spread butter is all you need for a camp knife unless you expect to clean game.
Jim

Ah the joys of language. No wonder we have so many problems in the world when what I call sharp, you call dull